GEOS managed to offer nearly all the functionality of the original Mac in a 1 MHz computer with 64 Kilobytes of RAM. It wasn't an OS written to run on a generic x86 chip on a moving hardware platform. It was written using immense knowledge of the hardware and the tricks one could use to maximise speed. Note:After a small break, here is another one of the articles for the Alternative OS contest.

I can't say I know a lot about NeXT systems, so indeed, you may be true. There are two main strains of GEOS, the 6502 version, and the x86 version. Both are entirely different operating systems. PC/GEOS which included the object orientated UI model, was started around 1989.

PC/GEOS's UI model had a few extra tricks up its sleeve though. PC/GEOS's UI was entirely object orientated. When Brian describes being able to change one thing into another, he isn't talking about fancy skins. The UI elements in an app were described in data, and the UI would represent that data according to the UI being used.

For example, a menu in a program could be realised as a menu, or a bullet list, or a folding tree structure, or, anything you could imagine with that dataset. This goes far beyond simple skinning in KDE, or even Cocca on OS X.